In recent years, a secondary battery, which can be charged and discharged, has been widely used as an energy source for wireless mobile devices. In addition, the secondary battery has attracted considerable attention as a power source for electric vehicles (EV), hybrid electric vehicles (HEV), and plug-in hybrid electric vehicles (Plug-in HEV), which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles that use fossil fuels.
In addition, technology related to an electric power storage apparatus that stores electric power and stably supplies the stored electric power to a power system when needed has been developed. The electric power storage apparatus is an apparatus that stores electric power when electric power demand is low and supplies the stored electric power in the event of overload or emergency. The electric power storage apparatus has the effect of improving both the quality of electric power and energy efficiency. In particular, markets for a household electric power storage apparatus and a middle-sized industrial or commercial electric power storage apparatus have been rapidly expanding, because such electric power storage apparatuses are related to smart grid technology.
Meanwhile, in order for a battery module to provide the output and capacity required by a predetermined apparatus or device, it is necessary for the battery module to be configured to have a structure in which a plurality of battery cells is electrically connected to each other in series or in parallel. In addition, it is necessary for the battery module to be configured to have a structure that is easily extendable and remains stable as the capacity of the battery module is increased.
In particular, in a case in which a plurality of battery cells is used to constitute a battery module, a plurality of members, such as bus bars and power cables, is needed for mechanical fastening and electrical connection between the battery cells, and a cooling structure must also be included. As a result, a process of assembling the members is very complicated. In addition, in a case in which it is necessary to extend the battery module, it is difficult to modify the structure of the battery module. Furthermore, a plurality of components is additionally needed, which increases the cost of manufacturing the battery module.
In addition, during the manufacture of a battery module which includes a plurality of components and the structure of which is therefore complicated, it is difficult to detect incorrect assembly of the battery module. Incorrect assembly of the battery module may decrease the safety and reliability of the battery module and may increase a defect rate of the battery module.